Carburetor fuel nozzle construction



Aug. l1, 1959 E. oLsoN cARBUREToR FUEL NozzLE CONSTRUCTION Filed Aug. 1,1957 wir IN VEN TOR. P9/vez a/z riz-'P ATTORNEY ite States PatentCARBURETOR FUEL NOZZLE CONSTRUCTION Elmer Olson, Rochester, N.Y.,assigner to General Motors Corporation, Detroit, Mich., a corporation ofDelaware Application August f1, 1957, Serial No. 675,721

Claims. (Cl. 261-41) The present invention relates to a charge formingdevice for an internal combustion engine and more particularly a fuelcluster assembly therefor.

In a carburetor utilizing an air actuated throttle anteriorly of amechanically actuated secondary throttle the flow of fuel is undesirablydelayed by the introduction of fuel into the induction passage at apoint anteriorly of the air actuated throttle. A carburetor of this typeis shown in copending application Serial No. 257,578, Braun, filedNovember 2l, 1951, now abandoned. In the previous type of fuel supplysystems as illustrated in the aforenoted application, when the pressuredifferential across the air actuated throttle reaches a suiciently highvalue to begin opening said throttle the flow of fuel through thesecondary nozzle and cluster is delayed due to the initially small airow through the fuel booster venturi. As a result of the fuel ow delaythe fuel-air mixture is momentarily leaned out with a consequentfall-olf in engine power output.

lt is the purpose of the present invention to provide a novel fuelcluster arrangement in which the fuel supplied to the induction passageis more closely responsive to engine demand as reflected by the openingmovement of the air actuated throttle. In the present device a fuelcluster arrangement is provided which insures that manifold vacuum willact on the fuel nozzle to insure immediate fuel ow as the air actuatedthrottle opens.

More specifically it is an object of the present invention to provide anair tube or cluster disposed in the induction passage and which tube isin communication with the fuel nozzle and further which tube is adaptedto project into the induction passage space between a mechanical and anair actuated throttle to insure that said tube is exposed to manifoldvacuum at any time the mechanical throttle is open.

The details of the present invention as well as other objects andadvantages are set forth in the description which follows.

In the drawing:

Figure l shows a partially sectioned carburetor embodying the presentinvention;

Figure 2 represents a modified form of the present invention; and

Figure 3 illustrates an air actuated throttle adapted for use with thepresent invention.

A carburetor is shown generally at 10 and, except as will be hereinafterspecifically pointed out, is adapted to function in substantially thesame manner as the aforenoted Braun carburetor. The present carburetorwill be described only in sufficient detail to provide a properunderstanding of the operation of the instant invention.

A primary induction passage is shown at 12 and includes a throttle valve14 disposed therein. A choke valve 16 is likewise disposed in theprimary induction passage. A secondary induction passage 18 includes athrottle valve 20 and an air ow actuated throttle 21 anteriorly thereof.The throttles 14 and 20 are coupled for mechanical operation andcooperate in the manner set forth in the copending Braun application.

,In Figure 1 a fuel cluster is shown generally at 22 and includes asecondary or fuel booster venturi 24, an air passage 26 communicating atone end with the venturi 24 and having an atmospheric opening 28 at itsother end. A secondary fuel nozzle 3) is supported from the fuel cluster22 and extends within the secondary fuel well 32. Under high poweroutput conditions, e.g. the secondary throttles 20 and 21 open, the airilow through the secondary or booster venturi 24 will draw air acrossthe beveled edge 34 of the secondary fuel nozzle 30 projecting withinthe air passage 26 thereby aspirating fuel into the secondary inductionpassage 18.

When the pressure differential across the unbalanced throttle 21 justreaches a value sufficient to begin opening the secondary throttle,however, there is insuiicient air ow through the booster venturi 24 toinsure adequate fuel flow into the induction passage 18. As a result thecombustible charge is inappropriately leaned out. To correct thissituation, a tube 35 is disposed within induction passage 18 and isdependingly supported from the fuel cluster 22. Tube 34 communicateswith the air passage 26 intermediate the atmospheric opening 28 and thebooster venturi 24. The other end of the tube 34 projects through anopening 36 formed in the air actuated throttle 21 and terminatesposteriorly of the throttle when the latter is in a closed position. inthis way as the mechanically operated secondary throttle 20 opens thelower end of tube 34 will be exposed to manifold vacuum insuringimmediate fuel iiow through the secondary fuel cluster 22 as soon as theair actuated throttle 21 begins to open. Accordingly, the leaning of thefuel-air mixture previously experienced during the initial opening ofthe air actuated throttle is avoided in the present device. As soon asthe air ow past the air actuated throttle 21 reaches a suiciently highvalue the secondary venturi 24 will begin to function in the normalmanner to supply the requisite quantities of fuel to the inductionpassage 1S.

As seen in Figure 3, the secondary air actuated throttle 21 is suitablyslotted at 36 to permit the tube 34 to project therethrough. In ordernot to interfere with the air flow actuation of throttle 21 the slot oropening 36 is formed in the smaller area portion of the throttle inrelation to the throttle shaft axis.

A modified form of the invention is shown in Figure 2 in which adifferent type of fuel cluster 40 is provided. In this modification thesecondary or booster venturi is eliminated and in its stead the fuelcluster is formed With a straight tube 42 extending from above thesecondary fuel Well 44 to below the air actuated throttle 46 through aslot 47 therein. ln this case secondary fuel nozzle 48 is providedhaving a bent portion 50 which extends into the tube 42 such that thebeveled end 52 of the nozzle is exposed directly to the air ow throughthe secondary induction passage 54. As in the modification of Figure 1with the air actuated throttle 46 closed and the posterior mechanicalthrottle partially open, manifold vacuum will at all times be active onthe fuel nozzle through tube 42 Ito insure immediate fuel flow upon theopening of the air actuated throttle.

In order to more effectively tailor the fuel How through tube 35, anorifice 6ft is provided in passage 26 intermediate the tube and boosterventuri 24. In this Way the resultant manifold vacuum force drawing airthrough passage opening 28 will be greater since the bleed ofatmospheric air from the induction passage end of passage 26 Will belimited by the size of orifice 60. Thus by selecting the appropriatesize of oriiice 60, the quantity of fuel flow through tube 35 may beestablished at a rate compatable with the desired operatingcharacteristics of a particular engine. It is, of course, apparent thatthe use oforice 60 will vary the respective percentages of fuel owthrough booster venturi 24 as well as through tube 35. Again the desiredfuel flow relationships between venturi 24 and tube 35 will bedetermined, at least pa'rt, by the engineoperating characteristicsdesired.

It is apparent that various additional structural modifications may bemade in the subject fuel cluster construction within the scope of thepresent invention, and that forms shown are merely for illustrativepurposes.

I claim:

l. A charge forming device for an internal combustion engine comprisingan induction passage including a mechanically actuated throttle valve,an air flow responsive throttle valve disposed in said induction passageanteriorly of said mechanically actuated throttle, a fuel well,.firsttube means projecting within said fuel well and extending within said`induction passage anteriorly of said air ow responsive throttle forsupplying fuel to said induction passage in response to air ow throughsaid passage, and second tube means disposed in said induction passageand communicating proximate one end with said first tube means, theother end of said second tube means extending within .the space betweensaid throttles.

2L A charge forming device for an internal combustion engine comprisingan induction passage including a mechanically actuated throttle valve,an air flow responsive throttle valve mounted on a shaft and disposed insaid induction passage anteriorly of said mechanically actuatedthrottle, a slot formed in said ow responsive throttle substantiallynormally to the shaft axis, a fuel well, first tube means projectingwithin said fuel well and extending within said induction passageanteriorly of said air ow responsive throttle for supplying fuel to saidinduction passage in response to air flow through said passage, andsecond tube means disposed in said induction passage and communicatingproximate one end with said first tube means, the other end of saidsecond tube means extending through said slot and into the space betweensaid throttles.

3. A charge forming device for an internal combustion engine comprisinga primary induction passage, a throttle valve in said passage, a chokevalve in said passage anteriorly of said throttle valve, a secondinduction passage, a mechanically actuated throttle disposed in saidsecondary induction passage, an unbalanced lthrottle valve disposed insaid secondary induction passage anteriorly of said mechanical throttle,a fuel well, a fuel nozzle projecting within said fuel well, an airpassage communicating with said fuel nozzle and projecting within saidsecondary induction passage anteriorly of said unbalanced throttle, saidair passage and fuel nozzle being adapted to supply fuel to thesecondary induction passage in response to the air ow past saidunbalanced throttle, a tube disposed within said secondary inductionpassage and communicating at one end with said air passage, said tubeextending longitudinally of said secondary induction passage andterminating at its other end posteriorly of said unbalanced throttlewhen the latter is closed, engine manifold vacuum being adapted to acton said tube whenever said mechanically operated throttle is at leastpartially open.

4. A charge forming device for an internal combustion engine comprisinga primary induction passage, a throttle valve in said passage, a chokevalve in said passage anteriorly of said throttle valve, a secondaryinduction passage, a mechanically actuated throttle disposed in saidsecondary induction passage, an unbalanced area flow responsive throttlevalve disposed in said secondary induction passage anteriorly of saidmechanical throttle, a slot formed in the smallest area portion of theflow responsive throttle, a fuel well, a fuel nozzle projecting withinsaid fuel well, an air passage communicating with said fuel nozzle andprojecting within said secondary induction passage anteriorly of saidunbalanced throttle, said air passage and fuel nozzle being adapted tosupply fuel to the. secondary induction passage in response .to the airtlow past said unbalanced throttle, a tube disposed within saidsecondary induction passage and communicating at one end with said airpassage, said tube extending longitudinally of said secondary inductionpassage and extending through said throttle slot to terminate at itsother end posteriorly of said unbalanced throttle when the latter isclosed, engine manifold vacuum being adapted to act on said tubewhenever said mechanically operated throttle is at least partially open.

5. A charge forming device for an internal combustion engine comprisinga primary induction passage, a throttle valve in said passage, asecondary inductionpassage, a mechanically operated throttle in saidrsecondary passage, an air flow responsive throttle disposed in saidsecondary passage anteriorly ofsaid mechanically operated throttle, afuel well, a fuel nozzle projecting within said fuel well, a venturidisposed in said induction passage anteriorly of said air flowresponsive throttle, an air passage communieating said venturi and saidnozzle whereby air flow through said venturi will cause fuel to flowthrough said air passage and into said induction passage in proportionto the velocity of said air ow, a tube disposed within said inductionpassage and communicating at one end with said air passage intermediatesaid venturi and said fuel nozzle, the other end of said tube extendinginto the space between said secondary induction passage throttles.

6. A charge forming device for an internal combustion engine comprisinga primary induction passage, a throttle valve in said passage, asecondary induction passage, a mechanically operated throttle in saidsecondary passage, an air ow responsive throttle disposed in saidsecondary passage anteriorly of said mechanically operated throttle, aslot formed in said tlow responsive throttle, a fuel well, aifuel nozzleprojecting within said fuel well, a booster venturivdisposed in saidinduction passage anteriorly of said airflow responsive throttle, an airpassage extending transversely of said induction passage andcommunicating said venturi and said nozzle whereby air ow through saidventuri will cause fuel to flow through said air passage and into saidinduction passage in proportion to the v elocity of said air flow, atube disposed within said inductlon passage and communicating at one endwith said air passage intermediate said venturi and said fuel nozzle,the other end of said tube extending through said slot and into thespace between said secondary induction passage throttles.

7. A charge forming device for an internal combustion engine comprisinga primary induction passage, a throttle valve in said passage, asecondary induction passage, a mechanically. operated throttle in saidsecondary passage, an air flow responsive throttle disposed in saidsecondary passage anteriorly of said mechanically operated throttle, afuel well, a fuel nozzle projecting within said fuel well, an air tubedisposed within said induction passage and extending longitudinallythereof, said air tube being open at bo-th ends and extending from apoint anteriorly of said fuel well to a point posteriorly of said airflow responsive throttle when the latter is closed, said fuel nozzleincluding a portion extending within said air tube, the portion of saidnozzle within said air tube being shaped so that the air ilow throughsaid air tube will create an aspirating effect on said fuel nozzle tocause fuel to tlow therethrough.

8. A charge forming device for an internal 'combustion engine comprisinga primary induction passage, a throttle valve in said passage, asecondary induction passage, a mechanically operated throttle in `saidsecondary passage, an air ow responsive throttle disposed in saidsecondary passage anteriorly of said mechanically operated throttle, afuel well, a fuel nozzle projecting within said fuel well, an air tube.disposed within said induction passage and extending-longitudinallythereof, said air tube bein g open at both ends and extending from apoint anteriorly of said fuel well to a point posteriorly of said air owrcsponsive throttle when the latter is closed, said fuel nozzleincluding a bent portion terminating in a bevelled end portion extendingwithin said air tube so that the air flow past said bevelled nozzleportion will create an aspirating effect on said fuel nozzle to causefuel to flow therethrough.

9. A charge forming device for an internal combustion engine comprisinga primary induction passage, a throttle valve in said passage, asecondary induction passage, a mechanically operated throttle in saidsecondary passage, an air flow responsive throttle disposed in saidsecondary passage anteriorly of said mechanically operated throttle, afuel well, a fuel nozzle projecting within said fuel well, a venturidisposed in said induction passage anteriorly of said air flowresponsive throttle, an air passage communicating said venturi and saidnozzle whereby air ow through said venturi will lcause fuel to flowthrough said air passage and into said induction passage in proportionto the velocity of said air ow, a tube disposed within said inductionpassage and communicating at one end with said air passage intermediatesaid venturi and said fuel nozzle, the other end of said tube extendinginto the space between said secondary induction passage throttles, andflow restricting means in said air passage intermediate said venturi andsaid tube.

10. A charge forming device for an internal combustion engine comprisinga primary induction passage, a throttle valve in said passage, asecondary induction pas- 6 sage, a mechanically operated throttle insaid se'condary passage, an air ow responsive throttle disposed in saidsecondary passage -anteriorly of said mechanically operated throttle, afuel well, a fuel nozzle projecting within said fuel well, a venturidisposed in said induction passage anteriorly of said air flowresponsive throttle, an air passage communicating said venturi and saidnozzle whereby air flow through said venturi will cause fuel to flowthrough said air passage and into said induction passage in proportionto the velocity of said air ow, a tube disposed within said inductionpassage and communicating at one end with said air passage intermediatesaid venturi and said fuel nozzle, the other end of said tube extendinginto the space between said secondary induction passage throttles, andorilce means in said air passage to limit the bleed of substantiallyatmospheric air into said air passage through said venturi.

References Cited in the file of this patent UNITED STATES PATENTS2,063,433 Grenat Dec. 8, 1936 2,573,093 Burson Oct. 30, 1951 2,617,638Udale Nov. 11, 1952. 2,752,133 Egerer June 26, 1956 2,793,844 Olson May28, 1957

